/Engine/Source/Editor/ViewportInteraction/Public/ViewportInteractor.h
Handles axis input and translates it to actions C++ Child classes are expected to to call there super versions of this. BP will have there "Receive" versions called from within these function and do not have to call there parents.They simply need to return if they handled the input or not.
bool HandleInputAxis ( class [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) & ViewportClient, const [FKey](API\Runtime\InputCore\FKey) Key, const float Delta, const float DeltaTime )